The invention relates to wind machines used for protection of citrus and avocado trees and other growth and crops against damage from cold or other climatic conditions. In some situations, a disturbance of the ambient air by forced air flow from the wind machine will suffice to dissipate the harmful effect of quiescent pockets or blankets of cold air which settle over, around and under trees and plants. Under extreme conditions, heating of some of this circulated air is required.
When the area to be serviced is generally flat land, the wind machine may be supported on a column or tower and the axis of the fan is usually disposed so as to direct the flow of air downward at an angle approximately 6.degree. below the horizontal in order to blow the air over all of the land at the proper height. The fan drive assembly is adapted to be slowly rotated through an arc of 360.degree. or less about a vertical axis so that a machine will operate over an extended area. The rotation of the fan drive assembly through a 360.degree. arc is at the rate of about 41/2 minutes per rotation.
Where the terrain is irregular and plantings are made on hillsides and rolling slopes, a special problem is presented in that the wind machines in order to be effective must cause the air flow to be at substantially the same height relative to the terrain as would prevail if the land were flat. Thus, if an ordinary wind machine were standing vertically on a slope, and were rotated with the fan shaft at a constant angle relative to the axis of rotation, the air flow directed over the descending terrain would flow too high and the air flow over the ascending terrain would be too low.
In the prior art tiltable wind machines have been used, but they required the tilting of the entire fan drive assembly and the driving means along with a supporting platform, all positioned on the top of a tower. The present invention provides an improvement over such wind machines in that only an outer portion of the fan shaft and the fan are tilted with respect to the terrain as the entire fan assembly is rotated.